Glad to hear you have the new CPU installed and getting some use out of it.
It sounds like it is running hot under a load. Anything in the 60's is hot for the Opty 180.
It will do it and all day long but that is warm for sure.
Let me check mine right now... Case temp is at 21c (70f) and CPU is 35c (95f). I did a few things when I pulled the Athlon 64 out and installed the Opteron.
I installed a new front fan (old one died years ago) and polished the heatsink where it contacts the CPU. I used AMD issued gray thermal compound. I actually scrapped it off the heatsink and then after I cleaned and polished the base of the stock heatsink I heated up the compound and dripped it on to the heatsink. I know you shouldn't reuse that stuff but it is better then the Radio Shack brand (IMO).
The case I use is old. It was built for a P3 system long ago. I have opened a port and installed a tube to allow about 20 to 40% of the air being pulled into the case to directly enter on the top of the CPU (as with many new case designs). This dropped the temp by 5 or 6 across the board.
What to do: Ensure you have good airflow through the case, cool air in the front (or side) and warm air out the back. More fans should be pulling warm air out then there are fans pushing cool air in - don't over do it or you could back draft the power supply, which in effect takes all the heat from the power supply and stores it in your CPU
What else.... with the computer off but still warm gently push down on the heatsink and twist it - ever so gently - side to side and ensure the compound has spread out. In the old 486 systems I would really twist but these 939 pins are a lot more delicate. Be careful but give it a try.
One more thing, default the BIOS, run it and see where the temps are. Stability in these chips come first from memory settings then heat tolerance. Get your memory set first - running the fastest (stable timings and clock) then push it up a little at a time. Once it fails pull back down a bit - call it done. I think you are on the right track there.
I would not overclock the FSB. Running as hot as it is you might very well cook it in a short period of time.
Over clocking will or better stated "can" decrease the MTBF of a CPU. There is proof that long term over clocking actually causes the gates in the CPU's to grow little hairs that will short out. IMO anyone that overclocks is not going to keep a system long enough to see the failure from overclocking unless they are extreme and have a catastrophic failure like a power spike or cooling failure and the chip bakes.
Hope this helps. I agree - AMD makes a good chip. (For the money)
Best of luck